Cam grinding machine



April 27, 1937. H. A. SILVEN CAM GRINDING MACHINE Filed Aug. 14, 1936 4 Sheets-Sheet l HERBERT A. SILl/EN umw m bah -wm N= QFSEM mam I H\ MNYNH .IMIhN Rh N9 t 2 Q2 1 E T2 r? Rm \l E L E IN mm hw -v m 5 1 Q B. hi NM Q X N E mum EN mmw mmm mm April 27, 1937. H. A. SILVEN CAM GRINDING MACHINE Filed Aug. 14, 1936 4 Sheets-Sheet 2 N M I W5 A T R E 5 R E H April 27, 1937. H. A. SILVEN CAM GRINDING MACHINE 4 Sheets-Sheet 5 Filed Aug. 14, 1936 DQQM N: bmhh L HERBERT A. SILVEN April 27, 1937. H. A. SILVEN 7 CAM GRINDING MACHINE Filed Aug. 14, 1936 4 Sheets-Sheet 4 HERSER T A. 5/1. l/EN macaw-w Patented Apr. 27, 1937 CAM GRINDING MACHINE Herbert A. Silven, Worcester, Mass., assignor to Norton Company, Worcester, Mass, at corporation of Massachusetts Application August 14, 1936, Serial No. 96,077

19 Claims.

This invention relates to grinding machines, and more particularly to an automatic camshaft grinding machine.

One object of this invention is to provide a simple and thoroughly practical machine for automatically grinding a plurality of cam blanks on an integral camshaft. A further object of this invention is to provide an automatic cycle control mechanism for controlling the feeding movement of the grinding wheel, the positioning movement of the work table, and the rocking movement of the cam toward and from the grinding wheel to grind successive cam blanks automatically to a predetermined size and contour. Another object is to provide an automatic cycle control mechanism in which a main control valve is actuated in timed relation with the wheel feeding movement. A further object is to provide an electrically controlled hydraulic mechanism for controlling the main control valve which in turn controls the admission of fluid to the table positioning cylinder and the rock bar cylinder.

A further object of the invention is to provide a combined wheel feeding and pilot valve which serves to shift a main control valve to control the cycle of operations of the machine. Another object of the invention is to provide an electrically operated mechanism to actuate the pilot valve after a predetermined cycle of operation to move the various parts of the machine into position for grinding the next cam, or which may be manually operated after a given cycle of operation to position the parts for grinding the next cam on the camshaft. Another object is to provide a mechanism to render the cycle control mechanism inoperative during the longitudinal movement of the table. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the fea- 40 tures of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings in which is shown one of the possible embodiments of the mechanical features of this invention,

Fig. 1 is a front elevation of an automatic cam grinding machine embodying this invention;

Fig. 2 is a diagrammatic view showing the piping diagram and electrical control circuit;

Fig. 3 is a fragmentary front elevation, on an enlarged scale, of the control mechanism;

Fig. 4 is a fragmentary cross sectional view, taken approximately on they line 4-4 of Fig. 3;

Fig. 5 is a fragmentary cross sectional view through the machine, taken approximately on the line 55 of Fig. 1, showing the electrical and manual control for the wheel feed and pilot valve;

Fig. 6 is a fragmentary sectional view, taken 5 approximately on the line 6-6 of Fig. 5, showing the connections between the manual and electrical controls for the wheel feed and pilot valve;

Fig '7 is a right-hand end elevation, on an enlarged scale, of the cycle control mechanism with the cover removed; and

Fig. 8 is a fragmentary plan view, on an enlarged scale, of the main control lever for starting the cycle of operation.

A cam grinding machine has been illustrated in the drawings having a base H) which supports a longitudinally movable work table II on the usual fiat way (not shown) and V-way 13. The base lll also supports a transversely movable wheel slide I5 on ways (not shown) for a transverse feeding movement toward and from the work supporting table II. The wheel slide l5 supports a rotatable grinding wheel 16.

The longitudinally movable Work table ll supports a pivotally mounted rock bar l8 which is 25 supported in bearings l9 and on the table II (Figs. 1 and 2) and is arranged so that it may be rocked about an axis which is parallel to the axis of the grinding wheel I6. The rock bar I8 is provided with a rotatable headstock spindle 22 and a headstock center 23. The rock bar l8 also supports a footstock 24 having a footstock center 25. The headstock center 23 and the footstock center 25 are arranged to rotatably support a camshaft 26 to be ground.

Master cams and roller In order that the cams on the camshaft 26 may be ground to a predetermined size and contour, it is desirable to provide a series of master cams 28 for controlling the rocking movement of the rock bar 18 so as to rock the camshaft 26 being ground toward and from the periphery of the grinding wheel 16 so as to generate a predetermined shape thereon. A plurality of master cams 28 are mounted on the headstock spindle 22 in axial alignment with the axis of the camshaft 26 being ground. A master cam roller or follower 29 is slidably mounted on a rotatable shaft 30 which is rotatably supported in brackets 31 and 32 (Fig. 1). 5 The master cam roller 29 is preferably indexed automatically as the table I l is moved longitudinally to position the master cam roller 29 opposite the master cam 28 which corresponds to the cam being ground on the cam shaft 26. The details 5'5" nism (not shown) of the master cam roller indexing mechanism have not been illustrated since this feature is not considered part of the present invention. For a detailed disclosure of the automatic shifting of the master cam roller, reference may be had to the prior United States Patent No. 1,783,755 to Trefethen and Belden and also to the United States Patent No. 2,022,178 to Belden and Silven dated November 26, 1935.

Table traverse The work supporting table H is moved longitudinally relative to the base it by means of a fluid pressure operated mechanism comprising a cylinder 32 which is fixed to the base It). A piston 40 is slidably mounted within the cylinder 39 and is connected by means of a piston rod M with a bracket 42 depending from table H. Fluid under pressure may be admitted either through a pipe 43 into a cylinder chamber M to cause the piston ll] and the table H to move toward the right (Fig. 2), or it may be admitted through a pipe 45 into a cylinder chamber 46 to cause the piston iii and the work supporting table H to move toward the left (Fig. 2). The admission of fluid under pressure to the cylinder 39 is controlled by a valve mechanism to be hereinafter described.

Wheel feed The wheel slide [5 may be moved transversely on the base i5 by a wheel feeding mechanism which may be actuated either manually or hydraulically, as desired. In the preferred construction, the wheel slide !5 is provided with a depending nut 55 meshing with a rotatable feed screw 5| which is rotatably sup-ported in the base i0 and is connected so that it may be rotated by a manually operable feed wheel 52 on the front of the machine base iii. The feed screw 5| is arranged so that it may be moved bodily in an endwise direction rapidly to move the grinding Wheel slide l5 and the grinding wheel it either toward or away from the work. This is preferably accomplished by connecting the rearward end of the feed screw 5! with a piston rod 53 which carries a piston 54 slidably mounted within a cylinder 55. The fluid pressure wheel feeding mechanism may be supplemented by a hydraulically operated dash pot feed controlling mecha- This dash pot mechanism may be arranged as shown in the patent to Silven No. 2,023,704 dated December 10, 1935. The dash pot feed control mechanism has not been illustrated in the present application, since this feature is not considered a part of the present invention. For further details of the dash pot con struction, reference may be had to the abovementioned patent. By utilizing a dash pot mechanism of this type, the wheel may be advanced rapidly by admitting fluid under pressure through a pipe 56 into a cylinder chamber 5'! to move the wheel slide l5 rapidly up to a position where the wheel 16 is about to contact with a cam to be ground. Then the dash pot piston is picked up by the piston rod 53 and the further advance of the grinding wheel in grinding the cam is controlled by the exhausting of fluid from the dash pot cylinder.

In order to remove the grinding wheel from contact with the work after the cam has been ground to a predetermined size and contour, the admission of fluid under pressure to the cylinder 55 is reversed and fluid is admitted through a ,pipe 58 into a cylinder chamber 59. A control or reversing valve 50 is provided to control the admission of fluid to the cylinder 55. In the position of the parts (Fig. 2), fluid under pressure from a tank or sump 6! within the base l5 passes through a pipe 62 and is forced under pressure by a pump 63 through a pipe 54 into a valve chamber 65 which is located between the valve pistons 66 and 6?. In the position of the valve 55 (Fig.2), fluid under pressure entering the valve chamber 55 passes outwardly through the pipe 58 into the cylinder chamber 59 to cause the piston 54 to move rearwardly or toward the right (Fig. 2) to withdraw the wheel slide 15 and the grinding wheel I6 from operative engagement with the work and into an inoperative position.

'During the rearward movement of the piston 55, fluid exhausts from the cylinder chamber 51, through the pipe 56, through a V-port 68, into a valve chamber 59, between a valve piston 10 and the valve piston 65 and through a passage H and exhausts through a pipe 12 into the reservoir Bl. When it is desired to cause an approaching movement of the grinding wheel it, the valve 60 is shifted so that fluid under pressure passing through pipe 54 enters the cylinder chamber 65 and passes out through V-port 58 and pipe 55 into' cylinder chamber 57 to cause the piston 54 to move toward the left (Fig. 2) and thereby cause the wheel slide l5 and the grinding wheel is to be moved transversely toward the camshaft 25 to be ground. During the forward feeding movement of the grinding wheel, fluid is exhausted from the cylinder chamber 59, through pipe 58, and passes through a V-port into a valve chamber l5 located between the valve piston 61 and a valve piston l5, and through the passage H and the exhaust pipe 12, into the reservoir El.

Rock bar actuating mechanism In order that the master cams 28 may be maintained in operative engagement with the master cam roller 29 during the grinding operation on a cam, a yieldable pressure device is provided which serves to yieldably maintain the master cam 28 in contact with the follower roller 29. As shown in the drawings, the rock bar I8 is provided with an arm 11. A cylinder 18 is pivotally supported on the bracket 3! by means of a circular clamping band l9. The cylinder '18 contains a piston 82 which is connected by a piston rod 8! with a stud 82 on the arm 71. A spring 33 surrounds the piston rod 8| and is contained within the cylinder l8 between the piston and a head (not shown) which is fixed in the lower end of the cylinder 118. The spring 83 is compressed to a sufficient extent to maintain the master cam 28 in operative contact with the master cam roller 29 during the grinding operation.

Hydraulic actudtionrock bar A fluid pressure mechanism is provided to rock the bar Hi to an inoperative position automatically before the table I i is traversed, so that the master cam 28 and follower 29 and product camshaft 26 and grinding wheel IE will be separated before the traversing of the table II is started. This mechanism may comprise a fluid pressure cylinder 85 having a piston 85 slidably mounted therein. The piston 86 is connected to a piston rod 81 arranged to contact with the arm i1. When fluid under pressure is admitted through a pipe 89 into a cylinder chamber 90 within the cylinder 85, the piston 86 moves downwardly andcontacts with the arm T! to rock the rock bar l8 and separate the master cam 28 from the follower roller29. A valve in the pipe line 89 may be regulated to control the downward movement of the piston 86.

Grinding wheel driving mechanism The grinding wheel I6 may be driven from any suitable source of power, such as a driving motor (not shown) mounted either on the base of the 4 machine or on the floor adjacent to the machine,

Table indexing movement The table II is traversed or indexed longitudinally and automatically bymeans of a fluid pressure system, above described, which comprises a cylinder 39 containing a piston 49 which is connected by a piston rod M with the depending bracket 42 on the table II. The ad'- mission of fluid to either cylinder chamber 44 or 46 is controlled by a table controlling or reversing valve 9|. Fluid from the pump 63 passes through a pipe 92, through a pipe 93, into a valve chamber 94 between valve pistons 95 and 96. The pipe 45 is connected between the valve III and the cylinder chamber 46, and a pipe 43 is connected between the valve SI and the cylinder chamber 4-4. It will be readily apparent from this disclosure that when the table reversing valve 9| is in the position illustrated in Fig. 2, no fluid is admitted to either of the cylinder chambers and the table I I will remain stationary. The valve BI is provided with a valve stem 97 which is operatively connected to a manually operable control lever 98 mounted on a rock shaft 99. A short lever I00 is mounted on the rear end of the rock shaft 99 and has apin IIlI engaging a spool I92 on the valve stem 91. It will be readily apparent from this construction that when the lever 98 is moved in a clockwise direction, the valve stem 91 will be moved toward the left, as viewed in Fig. 2, so as to admit fluid under pressure through the pipe 43 to the cylinder chamber 44, and cause a movement of the table II toward the right (Figs. 1 and 2). Similarly, the valve stem 9'! moves toward the right (Fig. 2) so as to pass fluid through the pipe 45 into the pipe 46 to move the table I I toward the left (Figs. 1 and 2).

The lever 98 is normally held in a broken line position 98a or 98b by means of an arrow point I05 on the lever I which is engaged by a spring* pressed roller I96. The lever, 98 is in a broken line position 98a, while the table I I is indexed intermittently in a direction toward the right (Figs. 1 and 2). The lever 98 is in the broken line position 9% (Fig. 3), while the table II is being indexed toward the. left, as indicated in Figs. 1, 2 and 3. The valve stem 91 is normally held in a position to admit fluid through the pipe 43 or the pipe 45 to the cylinder 39. The admission of fluid through the pipe 93, to the valve BI, is controlled by a main control valve, as will be hereinafter described.

An actuating mechanism is provided for the valve so that movement of the work supporting table I! operates to close the valve 9| so that when the table is traversed through a predetermined distance to position the next cam on the product camshaft 26 in operative relation with the grinding wheel I6, the valve 9I is automatically closed to stop further table movement.

This is preferably accomplished by means of a dog bar IIII which is adjustably mounted on the front edge of table II by means of bolts in elongated slots. The dog bar I I0 is provided with elongated slot III which serves to support and guide a plurality of adjustable dogs II 2. The dogs II2 may be adjusted along the bar to conform with the spacing of the cams on the camshaft 26 to be ground. The dog bar, if necessary for any variation in successive camshafts, may be adjusted longitudinally of the table without upsetting the adjusting of the individual dogs. In order that the control lever 98 may be moved in the direction of the movement of the table II, it is necessary to provide a secondary actuating lever for cooperating with the table dogs. As illustrated in the drawings, a dog lever I I4 is pivotally mounted on a stud I I5. The lower end of the dog lever H4 is provided with a projecting pin IIS which rides in a cylindrical aperture H1 in the lever 98. 1

Assuming the lever 98 is positioned as shown in Fig. 3, that is in a neutral position for starting of the grinding cycle, with the dog lever I I4 in contact with the. table stop dog I I9 which is adjustably mounted on the table II, the lever 98 is thrown either manually or automatically into position 98a to move the valve stem 91 and admit fluid through pipe 43 into cylinder chamber 44 to start the movement of the table I I in a direction toward the right, as viewed in Figs. 1, 2 and 3. This movement traverses the camshaft 25 supported by the table II to move the first product cam on the shaft 26' into operative relation with the grinding wheel I6. The traversing movement continues until the dog lever I I4 is engaged by the first dog II 2. The dog lever H4 is rocked into the position illustrated in Fig. 3, swinging the pin I I6 into engagement with an adjustable stop screw II8, or if the table II is indexed to the left, with an adjustable stop screw II9, both of which are adjustable with relation to the lever 98. When the table II is indexed to the right, the lever 98 swings from the position 99a into the full line position 98, as illustrated in Fig. 3, with the arrow point I05 depressing the spring-pressed roller I06. The parts, however, are adjusted so that the arrow point I does not reach the high point on the spring pressed roller I09, so that the roller is at all times exerting a pressure tending to move the lever 98 either in a clockwise or counterclockwise direction. The swinging of the lever 98 from position 98a into full line position, as indicated in Fig. 3, moves the valve stem 91 into the position as illustrated in Fig. 2, cutting off fluid under pressure from both of the pipes 43 and 45, thereby stopping the movement of the work carrying table I I. By adjusting the position of the dogs I I2 along the dog bar I I0, the stopping position of the table II may be adjusted, as desired, so that the product cams, will be positioned successively in operative relation with the grinding wheel.

The dog lever H4 is slidably mounted on the stud I I5 so that it may be thrown out of the path of the table dogs II2 to permit a further traversing movement of the table II. A lever I20 is pivotally mounted on a stud I2I and at its upper end is formed as a yoke having opposed pins I22 and I23 engaging slots in opposite sides of a hub I24 on the dog lever II4. When the lever I20 is moved from the full line position (Fig. 2) and rocked in a clockwise direction, the dog lever H4 is moved rearwardly or toward the right (Fig. 2) on the stud H5, out of the path of the table dogs H2,

so that the table II may be indexed to position the next cam in operative relation with the grinding wheel. A spring I normally maintains the dog lever I I4 in alignment with the table dogs II2 during the indexing traverse of the table II. This movement is preferably accomplished in timed relationship with the other operating mechanisms of the machine. A fluid pressure cylinder I2I is mounted within the machine base and is provided with a piston I28 having a piston rod I29 engaging an end I30 of the lever 520. A spring I3I which surrounds the piston rod I29 serves normally to retain the piston in its rearward or inoperative position. Fluid under pressure is admitted through a pipe I32 into a cylinder chamber I33 in timed relationship with the other operating mechanisms of the machine, to rock the lever I20 in a clockwise direction (Fig. 2) and thereby slide the dog lever II4 into an inoperative position out of alignment with the table dogs H2. This mechanism is preferably connected to a main control valve which will hereinafter be described so as to be operated automatically in timed relation with the other movements of the machine.

When the table H is indexed longitudinally, the longitudinal movement thereof continues until a table dog I I2 eigages the dog lever I I4 and rocks the dog lever and, through the connecting parts, the control 98, so that the arrow point I05 rides up on the spring pressed roller I06 until the control lever 98 assumes the full line position as shown in Fig. 3, in which position the table control or reverse valve 9I is in a neutral or stop position, cutting off fluid under pressure from the cylinder chambers 44 and 46 of thetable cylinder 39.

Table pilot valve ter the table II has been indexed intermittently for grinding successive cams on the camshaft 25, it is then desirable to shift the table index control valve 9I into a reverse position so that the arrow point I05 rides on the opposite side of the axis of the spring pressed roller I06. This is preferably accomplished by means of a pilot valve I35 which is of a balanced piston type and is normally held in a neutral or inoperative position by means of a spring I36. When the table reaches its end position in its movement toward the left, a depending projection on an adjustable truing dog I3! mounted on the table II (Figs. 1 and 3) engages the upper end of a pilot valve lever I38 and rocks it so as to move a valve stem I39 toward the right, as viewed in Fig. 2, so as to admit fluid which enters through a pipe I40 and a valve chember I4I into a pipe I42 which passes fluid under pressure into a valve chamber I43 at one end of the table reversing valve 9|. This pressure moves the valve stem 97 so that the control lever 98 and the arrow point I55 pass over the high point on the spring pressed roller Hi6 and shifts the valve 9| into a reverse position, so that after truing of the grinding wheel the table II is ready for an intermittent traversing or indexing movement in a direction toward the right, as viewed in Figs. 1, 2 and 3.

Wheel truing mechanism In a machine of this type, it is desirable that the grinding wheel be trued automatically in between operations so that a trued grinding wheel face will be presented at the start of each grinding operation. A truing apparatus comprising a bracket I45 is fixedly mounted on the table II and carries a truing tool which may be adjusted relative to the bracket I45 by means of a micrometer mechanism I46. The details of the truing mechanism have not been illustrated in detail, since this feature is not considered part of the present invention. For further details of this mechanism, reference may be had to the U. S. patent to Belden and Silven No. 2,022,178 dated November 26, 1935. After the last cam on the shaft has been ground, the wheel moves to an extreme rearward position with the piston 54 engaging the rear end of the cylinder 55 (Fig. 2). The table is then given an additional traversing movement to carry the previously adjusted diamond or truing tool across the operative face of the grinding wheel I5, while it is in its extreme rearward position.

Slow traveTse-truing The normal traversing or indexing movement of the table is comparatively rapid to reduce the loss of time between successive grinding operations. The normal table speed is not at all suited for a truing operation which requires a very slow, uniform relative traversing movement between the truing tool and the grinding wheel. To obtain a slow traversing movement of the table, a suitable slow feed or throttle valve I is provided. When fluid is exhausted from the cylinder 39 through either pipes :23 or 45, it passes through either a valve chamber I5I or I52, pipes I53 or I54 respectively, and then through a valve chamber I55 or I55 in the pilot valve I 35 and through a common exhaust pipe i5'I which enters a valve chamber I 58 in the feed control valve I55. A V-port I59 normally is wide open, permitting unrestrained exhaust of fluid from the cylinder 39. When the table I I indexes or traverses from the last cam on the camshaft and moves toward a truing position, a depending cam surface I52 on the truing dog I3! strikes a roller I63 which is mounted on the upper end of a spring pressed plunger I64. The lower end of the plunger engages a rock arm I55 mounted on the outer end of a rock shaft I66. The other end of the shaft I66 carries a rock arm I6! which is connected by a pin I68 to move a valve stem I69 of the slow speed valve I50. When the cam surface I52 moves the roller I63 downwardly, it rocks the shaft I66 and arm I81 and the valve stem I69 moves a valve piston I10 toward the right (Fig. 2) to partially close the V-port I59, thereby restricting the exhaust of fluid from the table traversing cylinder 39 so as to produce a slow traversing movement of the table I I and the diamond or truing tool across the operative face of the grinding wheel I6.

At the same time the slow speed valve moves to throttle the exhaust of fluid to cause a slow truing movement of the table I I, a pipe I?! is uncovered by movement of a valve piston I'IZ to admit fluid under pressure from a pipe I85 through a valve chamber I13 into the pipe I'II, into a cylinder chamber I9I, toactuate a lever I92 and thereby stop the wheel spindle reciprocation during the truing operation. The table continues its truing movement toward the left until the pilot valve lever I38 engages .9, depending projection on the adjustable truing dog I31 to move the pilot valve I35 from a neutral position and admit fluid under pressure into the valve chamber I43 of the table traverse valve 9| to reverse the direction of movement of the table. The table moves slow- 1y to pass the diamond across the face of the grinding wheel on its return stroke. The slow movement continues 'until the roller I63 rides p he cam surface I62 on the dog I31 as the table approaches the first cam on the camshaft 26 into position for starting the next grinding cycle. A spring I91 connected between the lever I 61 and a stud I38 on the valve I55 serves to return the valve stem I69 to its normal position so as to uncover the pipe I1I to allow fluid to exhaust from the cylinder chamber I 9|, through the pipe I1I, a valve chamber I99, a pipe 299, a pipe 258, into the reservoir 6|, thus allowing a spring 292 to swing the lever I92 to start the wheel spindle reciprocation for grinding the next camshaft. At the same time, the V-port I 59 is uncovered and unrestricted exhaust of fluid from the table traverse cylinder 39 starts the table IIzmoving at its normal traversing or indexing speed.

While the apparatus shown is set to pass the truing tool across the faceof the wheel once in each direction, it is possible to adjust the truing dog I31 so that a cam actuated star-wheel will provide a greater number of passes of the diamond across the operative face of the grinding wheel, if desired. Details of construction of the truing dog have not been illustrated in the present case, since this feature is not considered part of the present invention. Reference may be had to the prior United States patent to Belden and Trefethen No. 2,022,178 dated November 26, 1935 for details of disclosure of the truing dog.

Main control valve In a machine of this type, the mechanisms function automatically to successively grind a plurality of cam blanks on a camshaft to a predetermined size and contour, and it is essential that all of the mechanisms be properly timed. Inasmuch as most of the mechanisms of the machine are controlled by fluid pressure mechanisms, it is desirable to provide a main control valve I15 therefor, having a valve stem I14 formedintegral with a hollow valve member having valve pistons I16, I11, I18, I19, I80, I8I and I82 formed integrally therewith. Fluid under pressure from the pump 63 passes through the pipe 92 into a valve chamber I83 in the main control valve I75. Fluid under pressure pass- I83 through es from the valve chamber the pipe I85 to the slow speed or throttle valve I59, Fluid under pressure from the Wheel feed,cycle pilot valve Wheel to vibrate and thereby to produce inaccuracy in the work piece. It is one of the objects of this invention to provide acontrol mechanism whereby the grinding wheel I6 is removed from operative contact with the cam being ground before the longitudinal shifting of the work table II or the rocking of the rock bar I8 to an inoperative position. This is preferably accomplished by utilizing the grinding wheel feed control valve 59 as a control valve to control the admission of fluid to the wheel feed cylinder 55 and also to serve as a cycle pilot valve whereby fluid under pressure passes through the pipe 64 into the feed control. valve chamber 65. In the position of the parts as illustrated in Fig. 2, fluid under pressure passes out through the pipe 58 and a pipe 232 into a chamber 233 at the right-hand end of the main control valve H5 and serves to move the main control valve E75 into the position illustrated' in Fig. 2. p

A spring 234 serves normally to hold the wheel feed valve stem 235 to the right, as illustrated in Fig. 2, so that fluid under pressure entering the feed control and pilot valve chamber 55 passes out through the pipe 58 into the wheel feed cylinder chamber 59 to cause a rearward movement of the grinding wheel I 5 and also passes through the pipe 232 into the chamber 233 to normally hold the main control valve I15 in the position as illustrated in Fig. 2. When the main control valve I15 is moved into the position illustrated by fluid passing through the wheel feed valve 59, fluid is exhausted from a chamber 236 at the left-hand end of the valve I15, forcing fluid out through a pipe 231, through a valve chamber 69 in the wheel feed and cycle pilot valve 60, and out through the passage 1| and the pipe 12 into the reservoir ti.

A solenoid 249 is provided to actuate the valve 68 in one direction. As previously described, the solenoid 240 is connected by a link MI and a stud 2 i2 with a rock arm 243 which is pivotally mount-V ed on a stud 24a. The upper end of the rock arm' 253 is provided with a pin 239 which engages a spool shaped member 239 on the end of the stem of valve 60, as illustrated in Figs. 2 and 6, and serves when energized to shift the wheel feed valve 65 into the reverse position. In this posi-' tion of the valve pistons, fluid under pressure from the pipe 54 entering the valve chamber 65 passes through the pipe 56 into wheel feed cylin der chamber 51 to cause a forward feeding movement of the grinding wheel I6 and at the same time passes fluid under pressure through pipe- 231 into the end chamber 233 of the main control valve I15 to move the main control valve stem I14 toward the right (Fig. 2). This movement of the control valve I15 serves to admit fluid un-,

der pressure to the Various mechanisms of the machine. The solenoid 249 is preferably connected, in a manner to be hereinafter described, to control the movement of the wheel feed valve 69 which in turn controls the admission of fluid to shift the main control valve I15 after a predetermined time in the grinding cycle.

This movement of the control valve I15 admits. fluid under pressure through the pipe I32 into.

the cylinder chamber I 33 to shift the dog lever H4 out of the path of the table dogs I I2. When.

the dog lever II I moves out of the path of the table dogs I I2, the released tension of the spring-- pressed roller I96 serves to again shift the main control lever 98 into a broken line. position 98a sothat when the main control valve is again shifted into the position illustrated in Fig. 2, fluid will be admitted through the pipe 93 and. the pipe 43 into chamber 44 to cause an indexing movement of the table II. During the wheel feeding movement, when fluid under pressure is admitted through pipe 237 into chamber 235 at the end of the main control valve I75 to shift the main control valve I15 into a position toward the right (Fig. 2), the valve piston I76 covers the pipe 53 and thereby prevents fluid under pressure from passing into the table reversing valve M or to the table operating cylinder 39.

Cycle control mechanism In order to obtain the maximum efficiency from the machine, it is desirable to provide a suitable cycle control device which serves, after a cam has been rotated through a predetermined number of rotations in operative contact with the grinding wheel, to actuate the main control valve H5 and thereby to admit fluid under pressure to the cylinder chamber 9% to rock the master cams 28 and the product cams 26 away from the grinding wheel l5 and the master cam roller 29 respectively, and to admit fluid to the cylinder chamber 59 to move the grinding wheel 16 rearwardly to an inoperative position, and then to admit fluid under pressure to the table traverse cylinder 39 automatically to index the table ii to present the next cam 25 to be ground into operative relation with the grinding wheel l5. This is preferably accomplished by means of a cycle control counting device 245 which is com tained within a rectangularly shaped box on top of the bracket 35.

The counting device comprises a ratchet wheel 245 which is mounted to rotate on a shaft 241. A pawl 248'iscarried by a stud 249 on an arm 255 which is connected to move with a lever 25! so that the two arms 250 and 25! operate as a bell crank. The arm 25! is connected by an adjustable link 252, to the lower end of whichis connected a stud 82 on the arm Ti which is fixed to the rock bar I8. Each time the rock bar it rocks in a clockwise direction toward the grinding wheel, the bell crank lever 250-25l serves to rock the pawl 24B idly over the teeth of the ratchet wheel 245, and when the rock bar it is rocked by the master cams in a counterclockwise direction (Fig. 2) away from the wheel, it serves to cause a downward movement of the link 252, and the bell crank 25ll-25l serves to cause the pawl 248 to turn the ratchet wheel 24% a predetermined adjustable amount each time the rock bar moves through its rocking movement. The shaft 241 also carries an adjustable striker arm 253 which is arranged in the path of a lever 254 which serves to rock a support 255 which is mounted pivotally on a stud 256. The arm 255 carries a mercury switch 251. When the ratchet wheel 246 has been rotate-d through a predetermined extent, the striker arm 253 engages the projection 254 and rocks the arm 255 about its supporting stud 255 and trips the mercury switch 251. The tripping of the mercury switch serves to close the circuit and to energize the relay 265 which in turn closes a circuit to energize the solenoid 240 to shift the wheel feed valve 653 and thereby admit fluid under pressure to shift the main control valve H5 toward the right (Fig. 2).

It will be readily apparent from the foregoing that each time the rock bar I8 is oscillated in grinding a cam, the link 252 serves through the bell crank lever 258-45! to oscillate the pawl 248 to cause a movement of the ratchet wheel- 246. The link 252 is provided with adjustable nuts 262 and. a spring 263 by means of which the effective length of the link 252 may be adjusted to give the desired action to the pawl 243'. The extent of movement of the pawl may be controlled by means of an adjusting screw 23 which contacts with bracket 35, carried by the arm 25!, so that between the adjustment of the nut 252 and the screw 254, the extent of movement of the pawl may be adjusted as desired.

It is desirable to provide an adjustable cycle control mechanism which is arranged so that the grinding cycle may be changed readily without changing the speed of movement of the operating parts. This may be accomplished by adjusting the extent of movement of the ratchet pawl so that the grinding cycle may be shortened or lengthened, as desired, Without changing or affecting the speeds of the operating parts of the machine. In order that the extent of movement of the pawl 24% may be readily varied to permit adjustment of the number of ratchet teeth picked up at each actuation of the pawl 248, it is desirable to provide a means for readily adjusting the length of the arm 25I. The arm 25| is provided with a slot 255, and the link 252 is adjustably clamped in the desired location within the slot 255 by means of a clamping device 265. By adjusting the position of the clamping device 265 within the slot 2'55, the effective length of the lever arm 25f may be varied to adjust the extent of actuation of the pawl 248.

After a cam has been ground to a predetermined extent, it is desirable to provide a suitable mechanism for withdrawing the pawl 248 from the ratchet wheel 245 to reset the mechanism for controlling the grinding of the next'cam blank. This is preferably acomplished by providing a solenoid 267 which is provided with an upwardly extending rod 258 having a pair of adjustably mounted pins 259 and 215 which are arranged to engage a lever 2' which is formed as an extension of the ratchet pawl 248. A spring 212 surrounds the upper extension of the rod 268 and is interposed between the casing 245 and the nuts 273 which are screw threaded into the upper end of the rod 268. A spring 214 is connected to a stud 215 on a rotary member or hub 215 which carries theratchet wheel 246. The other end of the spring is connected to a stud 211 on the upper corner of the control box 245. It will be readily apparent from the foregoing disclosure that when the solenoid 261 is energized, as shown in Fig. 2, the rod 268 is pulled downwardly against the tension of the spring 212 and serves to rock the lever 2'il and the pawl 248 todisengage the pawl 218 from the ratchet wheel 246. When the pawls disengage the ratchet wheel 246, the released tension of the spring 214- serves to rotate the member 215 and the ratchet wheel 246 into its initial position, as illustrated in Fig. 2, so that the lower surface of the ratchet engages the adjustable stop 25| so that the mechanism is ready to control the grinding of the next cam blank.

Work rotation The headstock spindle 22 may be rotated by any suitable driving mechanism, such as an electric motor 280 which is connected through a suitable gear mechanism to rotate the work driving center 23 at the desired speed. In the preferred construction, a two-speed work drive is provided, such as that shown in the prior patent to Belden et al. No 2,022,178 dated November 26, 1935, to which reference may be had for details of disclosure. A manually operable lever 28! serves to move a clutch member 282 into engagement with the clutch members 283 and 284 to rotate the work driver at either a proper speed for rough grinding or for finish grinding, depending upon the operation for which the machine is set up. Details of the gear drive between'the headstock motor 280 and the center 23 have not been illustrated in the present case, since they are not considered part of the present invention. For a detailed disclosure of this mechanism, reference may be had to the prior United States Patent No. 2,022,178.

Start and trip lever A start and trip lever 29!! is pivotally mounted on the lever 2I1. The'lever 290 is arranged to swing in a substantially horizontal plane and is provided with a projecting lug 292 which is arranged to engage an extension of the pin I22 on the pivotally mounted lever I20. When the lever 29!) is moved toward the right (Fig. 3, the lug 292 engages pin I 22 and rocks the lever I about its pivot I2 I. This movement serves to move the dog lever I I4 out of the path of the table stop dog I I3. This movement allows the lever I00 to move in a clockwise direction due to the pressure of the spring pressed roller I06 on the arrow head I05 so as to move the valve stem 91 toward the left (Fig. 2) so as to admit fluid from the pipe 93 into valve chamber 94 and out through the pipe 43 into the table cylinder chamber 44 to cause the piston 40 and the table II to move toward the right, as viewed in Figs. 1 and 2. As soon as the dog lever Il l passes the table stop dog II3, the spring I rocks the lever I20 in a counterclockwise direction (Fig. 4) so that the dog lever H4 moves back into the path of the table dogs I I2. Movement of the table II toward the right continues until the dog lever I I4 engages the first table dog I I 2 to position the first cam on the camshaft 26 to be ground in operative relation with the grinding wheel I6. This movement rocks the lever 98 and the lever I00 to shift the valve stem 91 into the position illustrated in Fig, 2, so that the valve piston 65 cuts off the flow of fluid to pipe 43, thereby stopping the movement of the table II.

After the start lever has been shifted toward the right (Fig. 3) to shift the dog lever II 4 out of the path of the table stop dog H3 and start the table traversing movement or grinding cycle, the lever 290 is shifted back by means of the pin I22 contacting the lug 292 so that dog lever IM will be able to contact with the first table dog II2 but not closing the limit switch 283. However, when the table is stopped by the first table dog, lever 292 is moved towards the left to close the limit switch 299 to energize solenoid 269 to operate the wheel feed valve 62. This serves to move the pin 294 carried by the lever 290 into position 294a out of the path of the surface 295, which serves to allow a lever 296 to rock about its supporting stud 291 and allow the rod 298 of the limit switch 299 to move upwardly to close the circuit and render the mercury switch operative. Closing the limit switch serves to energize a relay 260 which inturn makes a circuit to energize the solenoid 240 which shifts the wheel feed valve 60 into the reverse position from that shown in Figs. 2 and 6, so that fluid entering the feed valve chamber 65 passes outwardly through the pipes 56 and 231 to move the main control valve I15 toward the right and also to start the forward advance of the grinding wheel I5 and its supporting wheel slide I5 (Fig. 2) to permit the exhaust of fluid from the rock bar cylinder chamber 90 so as to allow the rock bar I8 to rock in a clockwise'direction (Fig. 2) toward the grinding wheel I6 so that the master cam 28 engages the master cam roller 29.

The grinding wheel I S continues its forward feeding movement to grind the cams on the camshaft 26 to the desired size and contour and the wheel I6 then recedes, after which fluid is admitted to the wheel feed cylinder 55 to chamber 53 to cause a rearward movement of the grinding Wheel IS.

A normally closed limit switch 305 is arranged so that its actuating roller 301 is released by movement of the lever 98 in the position of the parts as illustrated in Fig. 2 and closes the limit switch 385 to energize the solenoid 251 to return the ratchet wheel 245 to its initial position. When the dog lever H4 is shifted out of the path of the table stop dog II3, the lever 9-8 moves in a clockwise direction into the position 984: which serves to shift the valve stem 91 to position the valve 9| for the next table traverse. At the same time the lever 98, which engages the roller 391 of limit switch 305; is rocked in a clockwise direction to break the circuit and thereby deenergize a relay 366 which in turn deenergizes solenoid 261 to render the ratchet pawl carriedby the lever 25!] and the ratchet pawl 218 of the cycle control mechanism 245 operative. The ratchet pawls remain in engagement with the ratchet wheel 246 during the indexing movement of the table II, the lever 98 being in the position 98a (Fig. 3), and the limit switch 305 being open to make the solenoid 261 inactive.

When the work table II reaches the extreme position to the right, is desirable to open the limit switch 298 so that the solenoids 2M and 261 are deenergized. This is preferably accomplished by providing a dog 308 on the table II. The dog 328 is arranged in the path of a vertioal plunger 309 which is connected toa lever 296 which cooperates with the rod 298. The lever 296 is pivotally supported on. a stud 291 and arranged so that when the dog 398 depresses the plunger 309, the lever 295 swings in a counterclockwise direction to depress the rod 298 and the limit switch 29-9, which serves to open the swtch, thereby rendering the cycle control mechanism 245 inoperative.

The dog 308 engages the plunger B and is depressed. The table reversing dog 3I8 rocks the lever I 38 which actuates the pilot valve I35 to cause the reverse valve 9| to reverse the movement of the table I I. This action rocks the lever 98 from position 98a to position 881) which allows the dog lever I I4 to clear the table dogs I! 2 so that the table I I will move to the truing position. This is accomplished by lever 88 contacting the adjustable screw am carried by a swinging lever 3II mounted on the stud 312. Lever 3H carries a latch 3I3 which rides on a pin 3M carried by the lever 98. During the indexing movement of the table II after the grinding operatiomthe lever 3| l assumes the position it has at the start of the grinding cycle. When the lever 98 swings the lever 3| I from the full line position (Fig. 3) to allow dog lever II4 to clear the table dogs II2 on the return stroke, the table stop dog II3, being of a pivotally mounted type allowing swinging in a counterclockwise direction only (Fig. 2), will let the dog lever H4 pass by, and upon com pletion of the truing operation will stop the table II in a loading position. In the last truing pass, the lever 98 is in the position 98a, and through pin 3M which contacts latch 3I3 to swing lever (H I to the full line position so that the dog lever I I4 will move by means of a spring I25 into further contacting relation with the table stop dog H3 at the end of a complete grinding cycle.

In order to prevent the grinding wheel from moving forward during the table traversin movement, the table II is provided with a series of dogs 308a which are mounted on an adjustable bar 22! carried by the adjustable dog bar III! and arranged to engage the plunger 309 and to open the limit switch 299 to render the cycle controlling mechanism 245 inoperative during the traversing movement between product cams. By varying the length of the stop dogs 308a, the cycle controlling mechanism 245 may be rendered inoperative during the traversing past a main bearing where the distance between cams on the camshaft 2% is greater than the spacing of the cams.

M antral-cycle control In the grinding of certain types of camshafts, it may be desirable to provide a machine in which the cycle of operation may be fully automatic so that all of the cams on the shaft will be ground without attention on the part of the operator, as shown and described above. It may be desirable, however, to so arrange the mechanism that, if desired, the cycle of operation may be manually controlled; that is after a cam has been ground, a manually operable lever is arranged to automatically separate the wheel and work, rock the rock bar to an inoperative position, and index the table longitudinally to present the next cam into operative relationship with the grinding wheel. Such a construction has been illustrated in Figs. 1, 5 and 6 of the drawings. A manually operable control lever 330 is pivotally mounted on a stud 33I carried by a bracket 332 fixed on the front of the machine base I0. The control lever 33!! is formed as a bell crank, the lower short arm of which carries a stud 333 which is connected to one end of a link or connecting rod 334, the outer end of which carries a detachable coupling 335. One end of a link 333 is pivotally connected by a stud 33? with the lever 243, and the other end is detachably connected by the coupling 335 with the rod 334. It will be readily apparent from this construction that when a con necting pin 338 connects the links 334 and 336, a manual movement of the lever 333' will operate through the rock arm 243 to shift the wheel feed valve 80 in either direction, depending on the direction in which the lever 33%) is moved. In case it is desired to operate the machine under a manually controlled cycle, the cycle control counting mechanism switch 3I6 is opened, thereby rendering the solenoid 243 inoperative. The pin 338 is inserted, as illustrated in Fig. 5, so that the wheel feed valve 6!! is controlled by the manually operable control lever 330 so that after the wheel It has been advanced toward the cam and ground a cam to a predetermined size, movement of the control lever 333 in a clockwise direction (Fig. 5) serves to shift the control valve 60. The shifting of the control valve 60 serves to admit fluid under pressure to the cylinder chamber 59 to cause a rearward movement of the grinding wheel I6 and at the same time serves to pass fluid under pressure to shift the main control valve H5, to admit fluid under pressure to the rock bar cylinder 85 to rock the bar and camshaft to an inoperative position, and also to admit fluid under pressure to the table traverse cylinder 39 to index the table I i to position the next cam on the camshaft 26 into operative relation with the grinding wheel It.

In case it is desired to operate the machine with an automatic cycle control to automatically grind all of the cams on a shaft without attention on the part of the operator, the pin 338 is removed, thereby disconnecting the links 338 and 336 to render the manually operable lever 335 inoperative. The switch 356 is then closed and the machine may be operated under automatic cycle control.

Operation Assuming the table I I to be in its extreme left hand or loading position, the machine is started into operation by first pushing an electric control button (not shown) to start the rotation of the grinding wheel I6, then pushing a second button (not shown) to start the rotation of the fluid pump 63. Push button 3 I 5 is closed to prepare for the rotation of the work driving motor 28!]. The Work piece, such as a camshaft 25, is then loaded into the machine and supported between the headstock center 23 and the footstock center 25. The Work driving clutch is then engaged by shifting the lever 28I to engage the movable clutch member 282 with either the clutch member 283 or 284, depending upon whether a finish grinding or rough grinding speed of the work is desired. The cycle control push button 3I6 is then closed to render the mercury switch 251 operative so that the machine is then under the control of the cycle counting mechanism 245. The hand lever 296 is then moved toward the right (Fig. 3). This movement serves to rock the lever 23!) about its vertical supporting stud so that the lug 292 engages the pin I22 to rock the lever I23 about its pivot IZI to move the dog lever II i out of the path of the table stop dog II3. This movement allows the released tension of the spring pressed roller IE5 to rock the levers 98 and I93 in a clockwise direction (Figs. 2 and 3) which serves to shift the valve stem 91 toward the left so that fluid under pressure passes through the pipe 93 into the valve chamber 94, passing outwardly through the pipe 43, into the cylinder chamber 44, to move the piston M3 and the table I I toward the right to bring the first cam on the camshaft 26 into operative grinding relation with the grinding wheel I6. Upon starting longitudinal movement of the table II, a dog 32I moves out of contact with a rod 322 to close a limit switch 323 to permit rotation of the headstock motor 28 Before the first cam 26 comes into operative position, the operator must push button 34!] to close a circuit and start work rotation. The longitudinal movement of the table I i continues until the first dog I I2 engages the dog lever I I4, which serves to rock the lever 98 from the position 98a to the position 98, thereby moving the valve stem 91 toward the right (Fig. 2) to cut out fluid from the pipe 43 and thereby stop the movement of table II. During the movement of the lever 98 to the position illustrated in Fig. 2, the limit switch 335 closes, serving to energize the relay 3% which in turn energizes the solenoid 231 to bring the cycle control mechanism 245 to its initial position.

After the movement of lever 23% to the right to move the dog lever H4, the lever 298 is swung toward the left to start the grinding cycle, the pin 2534 assuming position 294a. Upon further movement of table I I, the first dog 308a will disengage from plunger 333, allowing the limit switch 298 to close, and the solenoid 233 is energized to shift the wheel feed control valve 68 into the reverse position from that shown in Fig. 2, so as to admit fluid under pressure from the pipe 64, through the valve chamber 65, and through a pipe 56, into the cylinder chamber 51 to start the forward feeding movement of the Wheel slide I and grinding wheel I6 and also to admit fluid under pressure through the pipe 231,

into the chamber 236, to move. the main control valve I toward the right (Fig. 2). The table II has traversed to the first table dog I 52 before valve I15. covers the pipe 93. This movement of the main control valve I15 serves to.- cut out the flow of fluid-through the pipe 93 to the table reversing valve SI and serves to admit the flow of fluid under pressure through the pipe l 32, into the cylinder chamber I33, to move the piston ltd toward the left (Fig. 2) which serves to rock the lever I in a clockwise direction and thereby serves to move the dog lever II4 out of the path of the table dog I I2. At the same time the main control valve I15 is shifted, as above mentioned, fluid is allowed to exhaust from the cylinder chamber 90 to allow the rock bar I8 to rock so that the master cam 28 engages the master cam roller 29; Rotation of the master cam in contact with the master cam roller serves to rock the camshaft 26 to grind a cam blank to a predeterminedcontour. Each time the rock bar I8 rocks toward and from the grinding wheel, the cycle control counting device. 245 is operated and the link252 and the bell crankll-25I serves to rock the pawl to turnv the ratchet Wheel 246 until the striker 25.3 engages the lever 25.4 of the mercury switch supporting member to rock the mercury switch 251 and thereby break the circuit, which serves to deenergize the relay 260 to break the circuit and deenergize the solenoid 2% which in turn releases the tension of the spring 234 to permit the wheel feed valve 60 to move into the full line position, as illustrated in Fig. 2. This movement of the wheel feed valve 60 allows fluid passing through the pipe 64 into the valve chamber 65 topass out. through a pipe 232, into the valve chamber 233 of the main control valve I15. to movethe valve toward the left, into the position of the parts illustrated in Fig. 2. This movement of the-main. control valve I15 again opens the passage of fluid through the pipe 93 to the valve chamber 5 and allows it to pass out through the pipe 43, to the cylinder chamber 44-, to again index the piston 40- and the table II longitudinally to present the next cam into operative relation with the grinding wheel I6. This cycle of operation is continued until each one of the successive cams on the product camshaft is ground to the desired contour and size.

It will thus be seen that there has been provided by this invention apparatus in which, the various objects hereinabove set forth; together with many thoroughly practical advantages are successfully achieved. Asmany possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood. that all matter hereinbefore set. forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:-

1'. A cam grinding machine having a wheel slide, a work table and a. rock bar each. of which is operated by a separate fluid motor, a main control. valve in. control of the. work tablev and rock bar motors, a second control valve in con.- trol of said wheel slide motor and; main control valve, and a control mechanism operated inltimed relation with the rotation of said work to actuate said second valve.

2. A cam grinding machine having a wheel slide, a work table and a rock bar each of which is operated by a separatefiuid motor, a main control valve in control of the Work tablev and rock bar motors, afeed control. valve in control of said wheel slide motor and the main control valve, and a control mechanism. actuated in timed relation with the rockingof said bar to shift said feed control. valve. after a predetermined grinding operation has been completed.

3. A cam grinding machine having a wheel slide,.a work table anda rock bar each of which is operated by a separatefluid motor, a main control. valve in control of the work table and rock bar motors, a feed control valve-incontrol of said wheel slide motor and which also serves as a pilot valve to shift the main control valve, and. a control mechanism actuated in timed relation with the rocking of said bar to shift said feed control valve after a predetermined grinding operation has been completed.

4. A cam grinding machine having a transversely movable wheel slide, a longitudinally movable work table and a rock bar each of which is operated by a separate fluid motor, a main control valve in control of the work table and rock bar motors, a feed. control valve in control of said wheel slide motor and the main control valve, and a cycle control mechanism including a pawl and ratchet actuated by the movement of the rock bar to shift said feed control valve after a predetermined grinding operation has been completed.

5. A cam grinding machine having a transversely movable wheel slide, a longitudinally movable Work table and a rock bar each of which is operated by a separate fluid motor, a main control valve in control of the work table and rock bar motors, a Wheel feed control valve in control of said wheel slide motor and which also serves as a pilot valve toshift the main control valve, and a cycle control. mechanism including a pawl and ratchet actuated in timed relation with the movement of the rock bar to shift said feed control valve after a predetermined grinding operation has been completed.

6. A. cam grinding machine having a longitudinally movable work table and a rock bar to rotatably support a camshaft thereon, each of which is operated by a separate fluid motor, a main. control valve in control of said motors, a transversely movable grinding wheel slide, a fluid motor to operate said slide, and a control valve for controlling said wheel motor, said valve being connected to serve as a pilot valve to actuate the main control valve.

'7. A cam grinding machinecomprising a longitudinally movable Work table and a rock bar to rotatably support a camshaft thereon, each of which is operated by a separate fluid motor, a main control valve in control or". said motors, a rotatable grinding wheel and a transversely movable slide therefor, a fluid motor to control the transverse feeding movement of said slide, a control valve to control said wheel feed motor, and connections between said control valve and the main control valve whereby the control valve serves as a pilot valve for actuating the main control valve.

8. A cam. grinding machine comprising a longitudinally movable work' table and. a rock bar to rotatably support. a. camshaft thereon, each. of which is operated by a: separate fluid motor, a.

main control valve in control of said motors, a rotatable grinding wheel and a transversely movable slide therefor, a fluid motor to control the transverse feeding movement of said slide, a control valve to control said wheel feed motor, and connections between said control valve and the main control valve whereby the control valve serves as a pilot Valve for actuating the main control valve, said valves and connectionsbeing so arranged that the grinding wheel is withdrawn from engagement with the work before the bar is rocked to an inoperative position and before the table traverse is moved longitudinally.

9. A cam grinding machine having a transversely movable rotatable grinding wheel and supporting slide, a longitudinally movable work table and a rock bar, each of which is operated by a separate fluid motor, a main control valve in control of said work table and rock bar motors, a feed control valve in control of said wheel slide motor and arranged to actuate said main control valve, means including electrical solenoid to shift said feed control valve to cause a forward and rearward movement of the wheel slide, and a cycle control mechanism including an electric switch which is actuated in timed relation with the rocking of said rock bar to deenergize said solenoid and shift the feed control valve after a predetermined grinding operation to cause a rearward movement of the wheel slide.

10. A cam grinding machine having a longitudinally movable work table and a rock bar thereon for rotatably supporting a camshaft to be ground, each of which is operated by a separate fluid motor, a main control valve in control of said motors, means including a master cam and a follower to rock said bar to grind a predetermined contour on the cam blanks, a rotatable grinding wheel and a transversely movable wheel slide therefor, a fluid motor for operating said grinding wheel slide, a control valve in control of said wheel feed motor and to control said main control valve, electrically actuated means including a. solenoid to shift said feed control valve against the compression of a spring to cause a forward movement of the wheel slide, and a cycle control mechanism including a pawl and ratchet actuated electric switch which is actuated in timed relation with the oscillation of said rock bar during grinding to deenergize said solenoid.

11. A cam grinding machine having a longitudinally movable work table and a rock bar thereon for rotatably supporting a camshaft to be ground, each of which is operated by a separate fluid motor, a main control valve in control of said motors, a rotatable work support on said rock bar including a rotatable headstock spindle and a foot stock associated therewith, means including a master cam and a follower to rock said bar to grind a predetermined contour on the cam blanks, a rotatable grinding wheel and a transversely movable wheel slide therefor, a fluid motor for operating said grinding wheel slide, a control valve in control of said wheel feed motor and to control said main control valve, electrically controlled means to shift said feed control valve tocause a forward or rearward movement of the wheel slide, and a cycle control mechanism actuated in timed relation with the oscillation of said rock bar during grinding, and an, electric switch actuated by said cycle control mechanism to actuate said electrically controlled means and shift the feed control valve after a predetermined grinding operation to cause a rearward movement of the grinding wheel and a shifting of the main control valve.

12. A cam grinding machine having a longitudinally movable work table and a rock bar thereon for rotatably supporting a camshaft to be ground, each of which is operated by a separate fluid motor, a main control valve in control of said motors, a rotatable work support on said rock bar including a rotatable headstock spindle and a footstock associated therewith, means including a master cam and a follower to rock said bar togrind a predetermined contour on the cam blanks, a rotatable grinding wheel and a transversely movable Wheel slide therefor, a fluid motor for operating said grinding wheel slide, a control valve in control of said wheel feed motor and to control said main control valve, electrical solenoid to shift said feed control valve to cause an infeeding movement of the wheel slide, yieldable means to shift said feed control valve to cause a rearward feeding movement of the grinding wheel, and a cycle control mechanism comprising a pawl and ratchet mechanism actuated by the oscillation of said rock bar during grinding, and an electric switch actuated by said pawl and ratchet mechanism after a predetermined grinding operation to deenergize said solenoid and release said yieldable means to shift the feed control valve to cause a rearward movement of the grinding wheel and a shifting of the main control valve.

13. A cam grinding machine having a longitudinally movable work table and a rock bar thereon for rotatably supporting a camshaft to be ground, each of Which is operated by a separate fluid motor, a main control valve in control of said motors, a rotatable work support on said rock bar including a rotatable headstock spindle and a footstock associated therewith, means including a master cam and a follower to rock said bar to grind a predetermined contour on the cam blanks, a rotatable grinding wheel and a transversely movable wheel slide therefor, a fluid motor for operating said grinding wheel slide, a control valve in control of said wheel feed motor and to control said main control valve, electrical solenoid to shift said feed control valve to cause a forward movement of the wheel slide, a spring to shift the feed control valve to cause a rearward movement of the wheel slide, and a cycle control mechanism comprising a pawl and ratchet mechanism, connections between the pawl'and ratchet mechanism and the rock bar, and an electric switch actuated by said pawl and ratchet mechanism after a predetermined grinding operation to deenergize said solenoid and thereby release the tension of a spring to shift the feed control valve to cause a rearward movement of the grinding wheel and a shifting of the main control valve.

14. A cam grinding machine having a wheel slide, a work table and a rock bar, each of which is operated by a separate fluid motor, a main control valve in control of the work table and rock bar motors, a second control valve in control of the wheel slide motor and the main control valve, manually operable means to actuate said second valve to manually control the cycle of operation, a control mechanism operated in timed relation with the work rotation to actuate said second valve automatically to control the cycle of operation, and connections which serve to render operative either the control mechanism for manually or automatically controlling the grinding cycle.

15. A cam grinding machine having a transversely movable wheel slide, a longitudinally movable work table and a rock bar, each of which is operated by a separate fluid motor, a main control valve in control of the work table and rock bar motors, a control valve in control of the wheel slide motor and the main control valve, a manually operable lever to actuate said second control valve manually to control the grinding cycle, a cycle control mechanism including a pawl and ratchet actuated by movement of the rock bar to shift the feed control valve after a predetermined grinding operation, and means including detachable connections which are arranged to render either the manual control lever or the cycle control mechanism operative.

16. A cam grinding machine having a rotatable grinding wheel and a transversely movable slide therefor, a longitudinally movable work table and a rock bar thereon, each of which is operated by a separate fluid motor, control valves to control the admission of fluid to said motors, a cycle control mechanism including an electric switch which is actuated in timed relation with the rocking of said bar to control said valves, an electric limit switch in series with said cycle control mechanism, and a plurality of dogs on said table which are arranged to open said limit switch during the longitudinal traversing movement of the table to render the cycle control mechanism inoperative.

valve, a cycle control mechanism including an electric switch which is actuated in timed relation with the rocking of said bar to energize said solenoid and to shift the feed control valve after a predetermined grinding operation, a limit switch associated with said control mechanism, and means on said table to actuate said limit switch to render the cycle control mechanism inoperative during the longitudinal traversing movement of the work table.

18. A cam grinding machine having a rotatable grinding wheel and a transversely movable slide, a longitudinally movable work table and a rock bar, each of which is operated by a separate fluid motor, a main control valve in control of said work table and rock bar motors, a feed control valve in control of said Wheel slide motor and arranged to actuate said main control valve, electrically actuated means to shift said feed control valve to cause a rearward movement of the wheel slide, a cycle control mechanism including an electric switch which is actuated in timed relation with the rocking of said rock bar to energize said solenoid to shift the feed control valve after a predetermined grinding operation, a limit switch connected in series with said cycle control mechanism, and means including dogs on said table to actuate said limit switch when the table is moved longitudinally to render said cycle control mechanism inoperative during the traversing movement of the table and thereby to prevent an infeeding movement of the grinding wheel.

19. A cam grinding machine having a wheel slide, a work table and a rock bar, each of which is operated by a separate fluid motor, a main control valve in control of the work table and rock bar motors, a second control valve in con- 

